Unloading-valve for compressors.



G. F. STEEDMAN.

UNLOADING VALVE FOR COMPRESSQRS.

APPLICATION FILED JAN- 29, I916.

5,07 1 Q Patented Feb 6, 1917.

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ED STATES PATENT OFFICE.

enonen r. STEEDMAN, or sr. o Is raIssou-nr, assrenon r CURTIS & oo. MFG.00., or WELLSTON, MISSOURI, A conronnrion or MISSOURI.

UNLOADING-VALVE FOR COMPRESSORS.

Specification of Letters Patent.

Patented Feb. 6, 1917.

Application filed January 29, 1916. Serial N 0. 75,067.

To all whom it may concern:

Be it known that I, GEORGE F. STEEDMAN, a citizen of the United States,residingv at St. Louis, Missouri, have invented a certain new and usefulImprovement in Unloading- Valves for Compressors, of which the followingis a full, clear, and exact description, such as will enable othersskilled. in the art to which it appertains'tomake and use the same.

This invention relates to an unloading device for air or gascompressors, operating in the discharge pipe thereof, and whichautomatically unloads a portion of the discharge pipe adjacent to thecompressor whenever the compressor stops its compressing action, therebyfacilitating the starting up of the compressor against pressure in themains or tank beyond the unloading device, which the compressor issupplying.

In my Patent No. 686,778, of November 19, 1901, I show an unloadingdevicej operating in the discharge valve of a compressor and which isactuated by change inpressure in the reservoir or mains, but thisapplica} tion refers to a device which is actuated by the variation inthe flow of gas. or alr through the device. 1

It has been common practice to place check valve between the a1rcompressor and the storage tank, and provide a leak'oriiice in the pipebetween the check valve andrthe,

of gas or air through the pipe is resumed.

I am aware that similar unloading devices are successfully n use onwater pumps, but same are 'notcommerclally appl cable for use on airpumps, andf it is .the'ipurpose of my invention to' make an unloadingdevice which is practical and commercial for gas or air compressors.

Another object of my invention is to provide a device which requires noclose adjustment nor particularly fine workman:

ship or attention to operate successfully, so'that my devlce will giveservice to the general public;

Aiid still another object of my invention is to provide an automaticunloading device which can be easily and quickly adjusted, so as toaccurately regulate the close of the relief valve and closing of thecheck valve, after the-compressor starts to operate, thus enabling thedevice to be used with compressors of different capacities. Other objects and desirable features of my invention will be hereinafter pointedout.

Figure 1 of the drawings is a side elevational View of an apparatusconstructed in accordance with my invention; and Fig. 2 is alongitudinal sectional view of the valve structure arranged in thedischarge pipe leading from the compressor of said apparatus.

Referring to Fig. 1 of the drawings, A

designates a compressor of any suitable type th'at is'connected by meansof a discharge pipe' lito' the storage tank B. A valve structure of thekind illustrated in Fig." 2 is arranged in the discharge pipe 1 betweenthe compressor A and the storage tank B, so as to automatically unloadthe discharge pipe when" the compressor ceases endsiwith. threadedopenings for receiving the discharge pipes 1 and 1 and having apartition 2 which divides the interior of saidibody portion into twoseparate compartments or chambers. A check valve C is arranged in saidpartition so as to cut off communication between the two compartments orchambers of the valve body when the compressor A ceases to operate, anda relief valve or unloading valve D is arranged in said body portion 2at a point between the check valve and the compressor, so as toautomatically unload the discharge pipe after the compressor A hasstopped, or when the check valve O is on its seat. When the compressor Ais in normal operation the re lief valve D is closed and the check valveG is open, thereby permitting the medium compressed by the compressorto. flow through the discharge pipe into the stor age tank B without anyescaping through the port or orifice that the relief valve D controls.When the compressor ceases to op'erate the check valve 0 actsautofectively closes said orifice.

matically, to prevent the pressure in the storage tank from backing upinto the com-' pressor, and a means then becomes operative for causingthe relief valve D to open so as to permit the compressed medium in thatportion of the discharge pipe 1 between the compressor and the checkvalve C to escape. Itis immaterial, so far as my invention is concerned,what particular type ofrelief valve is used, but I prefer to use aneedle valve that controls a discharge port or orifice 3, said valvebeing opened automatically by means of an operating device 4 that isactuated by the check valve G. The stem 5 of the relief valve D isreciprocatingly "mounted in the bodyportion 6 of said valve and adjacentthe upper end of said stem is anenlarged portion 5 in which one or moregrooves 7 are formed, so as topermit the I medium in the discharge pipe1 to flow through saidgrooves and escape through the orifice 3when thestem 5 of the relief valve is raised, as shown in Fig. 2. \Vhen therelief valve D is closed the conical portion at the lower end of thestem 5 thereof side of the dischargeorifice 3, and thus ef- It is alsoimmaterial, so far'as my broad idea is concerned, what particular typeof check valve is used, butI prefer to use a valve G that comprises apiston portion 8 which fits snugly in a cylinder 9 in, the body portion2 of the valve structure, said piston portion being connected to thevalve C by a reduced portion or shank 10. 0n the underside of the valveC'is a distinct piston portion 11 that reciprocates in an open-endedsleeve 12 that forms part of the transverse dividing wall or partitionin the body portion 2 of the valve structure, saidsleeve being beveledat its upper end, as shown in Fig.2, so as to form a seat 13 for thevalve C. When the compressor A is in normal operation the check valve Cis held from its scatby the pressure of the medium that flows throughthe discharge pipe 1, the piston portion 8 of the check valve acting todampen the movement of said valve and tending to prevent it fromfluctuating between impulses of the compressor A. The piston portion 8and its cylinder 9 comprise what is ordinarily known as a'dash pot. Iprefer to usea valve with a dash pot, as it insures longer life. tothe-device, and noiseless op oration, but the dash pot is notessentially necessary to the. successful operation of the device. Thedashpot, if used, may be placed where convenient.

lVhenthe compressor ceases its compressing action the weight of thevalve C moves said. valve'downwardly toward its seat, but

if desired, a spring 1 1 can be arranged be-' tween the valve C and aremovable cap 9 that forms the upper end of the cylinder 9,

a bifurcated portion 16 that straddles the stem of the relief-valve Dand bears against the underside of a head 17 at the upper end of saidstem. The opposite end of the lever 4 is arranged in such a positionthat it will be engaged by a depending shank or stem 18 on the pistonportion 11 of the checkvalve C when said valve moves toward its seat,after the compressor A ceases to operate. In order that my improvedvalve structure may be used with compressors of different capacity, Ihave provided the relief valve D with an adjustable device 19 arrangedin the lower end of the body portion 6 of same for regulating thedischarge through the orifice 3. By changing the position of the device19 the rate of flow through the discharge orifice 3 when the compressorA is started can be varied so as to accurately regulate the time ofopening the check valve'C and the time of closing the relief valve. Inother words, the device 19 makes it possible to accurately adjust thevalve structure so that the ;check valve C will not open and the reliefvalve D will not close until after the compressor has acquiredsufficient speed to produce sufficient pressure to force the check valvefrom its seat. On the'underside of the body portion 2 of the valve is aremovable cap 20 that carries the relief valve D and the bracket 15 onwhich the operating lever 4 for the relief valve is mounted. 7

hen the compressor A is in operation the check valve C occupies such aposition that the depending stem18 on the piston portion 11 of same doesnot engage the relief valve operating lever 1, thus permitting therelief valve to be held seated by the internal pressure in the hollowbody portion 2 of the valve structure, or by any other suitable means,and consequently, preventing the medium flowing through the dischargepipe 1 from escaping through the unloading orifice 3. WVhen thecompressor A stops,the check valve C moves toward its seat and causesthe depending stem 18 thereon to ex ert sufiicient pressure on the lever4 to antomatically unseat the relief valve, and thus open the orifice 3.When the check valve C seats the relief valve D. Consequently, there isno possibility of the compressed medium in the storage tank B and theportion of the discharge pipe 1 between the valve structure and thestorage tank B backing up and escaping through the unloading orifice 3when the compressor stops, owing to the fact that the relief valve D isnot opened until after communication has beencut off between thetwochambers in the body portion 2 of the valve structure. In other words,the check valve is so constructed that communication between thereliefvalve and the storage tank is cut oif entirely, or almost entirely,before the check valve moves toward its seat sufiiciently to cause therelief valve to open. The relief valve D opens quickly and remains inits open position so long as the check valve C remains seated, thuspermitting the pressure to escape from the portion of the discharge pipe1 between the compressor and the check valve C. When the compressor isthereafter started the check valve C remains seated and the relief valveD remains open until the compressor has acquired sufficient speed tocreate sufficient pressure in the discharge pipe to overcome the forcethat holds the check valve seated. Some of the medium of course escapesthrough the discharge orifice 3 when the compressor is being started,but as soon as the pressure becomes great enough to unseat the checkvalve C, the relief valve D closes, and thus automatically cuts oif theescape of the medium through the unloading orifice 3. i

The piston portion 11 beneath the valve seat 13 of the check valve 0insures a con siderable aptitude of vertical motion to the check valve0, so that there is no refinement of adjustment necessary between thevalve C and the lever at, and reasonable wear to the different partsdoes not, therefore, aifect the proper sequence of operations.

The piston portion 11 also makes it possible for a large size reliefvalve, built according to my invention, to operate successfully on arelatively small compressor, as the piston portion 11 insures aconsiderable vertical travel to the valve C, irrespective of the volumeofair passing by the valve C. In other words, the piston portion 11determines the minimum travel of the valve C.

lVhen I speak of the compressor stopping, I intend to convey the thoughtthat the compressor shall either stop entirely or slow down considerablybelow its normal rate of operation, thereby causing a considerably lessvolume of air to pass through the relief valve than does under normaloperating condition of the compressor. I wish it also understood thatwhen I speak of air in the claims that I mean either air or any othergas. Nhen I speak of an unloading valve forthe discharge line, I meanthat portion of the discharge line between the check valve and thecompressor.

Having thus described my invention, what I claim and desire to secure byLetters Patent, is:

1. In an apparatus of the character described, the combination of acompressor, a storage tank, a check valve arranged in the discharge linefrom said compressor, an unloading valve for said discharge line, saidvalves being arranged out of alinement with each other, means forcutting off the flow of the medium in said discharge line when thecompressor stops, and means controlled by said check valvefor causingsaid unloading valve to open automatically before said check valveseats.

2. In an apparatus of the character described, the combination of acompressor, a storage tank, a check valve arranged-in the discharge linefrom said compressor, an unloading valve for said discharge line, saidvalves being arranged out of alinement with each other, means forcutting oif the flow of the medium in said discharge line when thecompressor stops, means controlled by said check valve for causing saidunloading valve to open automatically before said check valve seats, andmeans for regulating the discharge of the medium from said unloadingvalve.

3. In an apparatus of the character described, the combination of acompressor, a check valve arranged in the discharge line from saidcompressor, an unloading valve adapted to unload the discharge linebetween the compressor and the check valve, means for cutting olf theflow of the medium through the discharge line when the check valve isnear its seat, a dampening means combined with said check valve toprevent its rapid movement to and from its seat, and

after the flow of the medium through the discharge line has ceased.

4. In an apparatus of the character described, the combination of acompressor, a check valve arranged in the discharge line from saidcompressor, an unloading valve adapted to unload the discharge linebetween the compressor and the check valve, means for cutting 0d theflow of the medium through the discharge line when the check valve isnear its seat, and means controlled by said check valve for causing saidunloading valve to open automatically before said check valve seats.

5. In an apparatus of the character described, the combination of acompressor, a check valve arranged in the discharge line from saidcompressor, an unloading valve adapted to unload the discharge linebetween the compressor and the check valve,

means for cutting off the flow of the medium through the dischargeline'when the check valve is near its seat, a dampening means combinedwith said check valve to prevent. its rapid movement to and from itsseat, means controlled by said check valve for causing said unloading,valve to open auto- 7 matically before said check valve seats but afterthe floW' of the medium through the discharge line has ceased, and meansfor regulating the discharge of the medium from said unloading valve. 7r

- 6. An unloading check valve for air com pressors, comprising a bodyportion, a partition that divides said body portion into a receivingcompartment and a discharge compartment, said partition having anaperture provided with a check valve seat ar-' ranged adjacent thedischarge compartment and a piston valve sleeve arranged adjacent thereceiving compartment, a check valve operating in the aperture in saidpartition and provided with a piston valve portion-an ranged in thesleeve in saidpartition, a dampening piston portion arranged on thedischarge side of said check valve, a dampening cylinder arranged inalinement with said check valve that receives the said dampening pistonportion and thus prevents rapid movement of the check valve, and anunloadlng valve with a restricted opening in the reportion provided witha partition that divldesthe lnterlor of same llltO two c0mpartments,said partltion havlng an open- 'ended sleeve, a check valve having acylindrical portion that fits'in said sleeve, a piston'po'rtion on saidcheck valve-that fits in a' cylinder in said body portion, a springthat-exerts pressure on said check valve in a dlrection tendmg'to hold1t seated, a relief valve that controls adischarge' orifice leading fromone of said compartments, and a lever-interposed between said valves foreffecting the opening of said relief-valve.

'8. A valve structure, comprising abody portionprovided with a partitionthat divides the interior of same, into two compartments, said partitionhaving an openended sleeve, a check valve having a cylindrical portionthat fits in said sleeve, 9. piston portion on said check valve thatfits in a cylinder in said body portion, a relief valve that controls adischarge orifice leading' from one of said compartments, said reliefvalve consisting of a stem that is reciprocatingly mounted in abody'portion in l which said discharge orifice is formed, an

adjustable device for regulating the discharge of the medium throughsaid orifice, and an operating device for said relief valve that isadapted to be engaged by a portion on said check valve.

- In testimony whereof I hereunto afiix my signature in the. presence'oftwo witnesses, this 24th day of January 1916.

GEORGE F. STEEDMAN.

Witnesses:

L. L. BUGKLES, J. F. D. HOWELL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

' i Washington, 110.

